1. Field of the Invention
This invention relates to pumping arrangements and in particular to pumping arrangements for use in medical applications such as the intravenous supply of fluids to a patient.
This case also relates to the subject matter disclosed is commonly owned U.S. applications Ser. No. 07/430,851 filed Nov. 2, 1989, now U.S. Pat. Pat. No. 5,151,019 Ser. No. 07/744,350 filed Aug. 13, 1991, now U.S. Pat. No. 5,154,700 and Ser. No. 07/775,449 filed Oct. 15, 1991, which are hereby incorporated by reference into the present application.
2. Discussion of Background
In pumping applications involving intravenous supply of fluids it is common for deformable tubing, such as p.v.c. tubing, to be used to deliver the required fluid to the point of application. Where the supply rate and pressure is required to be carefully controlled, as is generally the case in medical applications, a serious problem can arise if the delivery tubing is restricted in any way (for example, by a patient rolling over onto it). Means can be provided to detect the resultant increase in pressure in the delivery tubing and disable the pumping action. However, if the restriction is removed (in the example given, by the patient rolling over again, off the tubing, or more likely by a nurse responding to an alarm also initiated by the means for detecting the increase in pressure) an undesirable surge of fluid to the point of application can result due to pressure retained in the delivery tubing.